Luck, whose recovery stalled multiple times following January 2017 shoulder surgery, sat out the preseason and regular season but slowly progressed following a second operation. He’s less than two months into a throwing program, but general manager Chris Ballard said Luck is following the prescribed routine to be ready for Week 1 of the 2018 regular season.

Those orders will include missing multiple days of practice during training camp.

At minicamp, Luck threw a Wilson TDS 1205, a standard high school football that is lighter than NFL footballs. But he also said he started throwing an NFL ball — “The Duke” — a few weeks ago and it “felt great,” despite a bit of a mental block building back up to it. He is currently “bridging” the gap between the lighter footballs and a regulation ball right now, also working in overhead tennis serves and throws with round balls to make the same motion with less stress on the shoulder. Luck threw “The Duke,” Wilson’s regulation NFL football, on Friday.

In an attempt to simulate a typical week during the regular season, Luck has been throwing four days a week: Three days in a row to simulate a typical practice week, and then an off day before a fourth day to approximate games.

Luck had not been on the field for the portions of Colts’ practices open to the media during organized team activities in recent weeks, but head coach Frank Reich told reporters he had been participating in individual drills. The signal-caller spent much of the offseason with throwing gurus Tom House and Adam Dedeaux, using weighted balls as part of his rehab.

The team has taken a very conservative approach in getting Luck healthy after the QB suffered pain in his throwing shoulder in his return to practice last October, nine months removed from shoulder surgery to correct an injury he originally suffered during the 2015 season. After the setback, he was shut down and missed the rest of the season. He spent a month in the Netherlands getting therapy on the shoulder.

“I had pain last year,” Luck said last Tuesday. “Pain, and I wasn’t being honest with myself about it. ... There’s not that right now.

“...It’s gone. That pain is gone, and it’s going to stay that way.”

The Colts begin the 2018 regular season Sept. 9 against the Cincinnati Bengals.